Negative-pressure balance system for gear box of centrifugal compressor

Abstract

A negative-pressure balance system for a gearbox of a centrifugal compressor includes the gearbox, a hermetically-sealed low-level oil collecting tank and a U-shaped negative-pressure balance pipe. The gearbox is connected to a respirator, and the back pressure of the respirator is a local ambient atmospheric pressure. The bottom of the gearbox and the low-level oil collecting tank are connected by an oil conduit. An oil demister communicated with the low-level oil collecting tank is mounted at the top of the low-level oil collecting tank. The oil demister at least includes a ventilation device. The respirator is communicated with a front-end lubricating point in the gearbox. One end of the U-shaped negative-pressure balance pipe is communicated with the respirator, and the other end of the U-shaped negative-pressure balance pipe is communicated with a rear-end lubricating point in the gearbox.

What is claimed is: 
     
       1. A negative-pressure balance system for a gearbox of a centrifugal compressor, comprising:
 the gearbox, wherein the gearbox is connected to a respirator, and a back pressure of the respirator is a local ambient atmospheric pressure; and 
 a hermetically-sealed low-level oil collecting tank, wherein the hermetically-sealed low-level oil collecting tank is located below the gearbox; 
 wherein, a bottom of the gearbox and the hermetically-sealed low-level oil collecting tank are connected by an oil conduit; 
 an oil demister communicated with the hermetically-sealed low-level oil collecting tank is mounted at a top of the hermetically-sealed low-level oil collecting tank, and the oil demister at least comprises a ventilation device, and a volume of ventilated air of the oil demister in operation is greater than a leakage amount from an internal space of the gearbox, wherein a negative pressure is established not only in the hermetically-sealed low-level oil collecting tank, but also in the internal space of the gearbox; 
 the respirator is communicated with a front-end lubricating point in the gearbox; 
 the negative-pressure balance system for the gearbox of the centrifugal compressor further comprises a U-shaped negative-pressure balance pipe, wherein a first end of the U-shaped negative-pressure balance pipe is communicated with the respirator, and a second end of the U-shaped negative-pressure balance pipe is communicated with a rear-end lubricating point in the gearbox. 
 
     
     
       2. The negative-pressure balance system for the gearbox of the centrifugal compressor according to  claim 1 , wherein the oil demister comprises a filter cylinder communicated with the hermetically-sealed low-level oil collecting tank, the filter cylinder is inside provided with a filter material, and the ventilation device is arranged on the filter cylinder. 
     
     
       3. The negative pressure balance system for the gearbox of the centrifugal compressor according to  claim 2 , wherein the ventilation device comprises a driving motor and a suction fan driven by the driving motor, and the hermetically-sealed low-level oil collecting tank is ventilated by the suction fan.